Shell Script: NSLookup DNS entry to see which server is LIVE

Here is a simple script which allows you to perform an NSLookup on a DNS entry to find out if the current host is Live or not.

This is useful if you have a mirrored backup server that shouldnt process any data unless its currently live. If a failover occurs, the backup server will then realise it's live and process the information which the other server was currently processing.

Code Snippet

1. #!/bin/sh
2. ################################################################################
3. # Does an NSLookup on a server DNS entry to determine which server is currently LIVE.
4. ################################################################################
5. #
6. # Get LIVE server and query current server
7. liveServer=`eval nslookup mgs | grep "Name:"`
8. currentServer=`eval hostname`
9.  
10.  
11. # Nslookup to see if this server is LIVE
12. echo "$liveServer" | grep $currentServer >/dev/null 2>&1
13.  
14. if [ "$?" -eq "0" ]; then
15.     echo "This IS the Live server"
16. else
17.     echo "This IS NOT the Live server"
18. fi
19.  
20.  
21.  
22. exit 0

End of Code Snippet